Abstract: For gas and water producing wells, accurate prediction of wellbore pressure drop is one of the vital methods for predicting gas well productivity. At present, most of predicting wellbore pressure drop models were established based on judging the flow pattern transition. Due to different judgment criteria, the pressure drop values calculated by different models under high and low gas flow rates varied greatly. In this paper, a visualized experimental setup was established to simulate gas-liquid flow in a horizontal well. Some experiments were conducted in different angles. Combined with the experimental data, the pressure drop calculation models commonly used in engineering were evaluated, and the pressure drop calculation models suitable for high and low gas velocity zones were optimized. Comparing with published data, mean absolute error of the new model is 9.17% in low gas velocity wells, and 6.53% in high gas velocity wells. It could provide reliable reference for the prediction of horizontal gas well pressure drop.